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How can I remove a record from a large Unix file ?

Posted on 2011-03-25
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Last Modified: 2012-05-11
I have a Unix file that has a bad record in it that needs removed.

The file is too large for vi, it says "No space left on device".

So how can I remove the bad record ? it has "MB6     0" in position 86 for 9.

Through other testing, I also know what record # it is.
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Question by:Alaska Cowboy
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Accepted Solution

by:
simon3270 earned 75 total points
ID: 35215827
If you have enough space to store the big file twice:

    sed NNd bigfile > bigfile.copy

where NN is the record number (e.g. "sed 2d bigfile > bigfile2" to remove line 2).
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Expert Comment

by:simon3270
ID: 35215845
This assumes that the "record" is a text line.  If this is a file sith some other format (fixed-length fields, binary values and so on) then "sed" won't work.
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Expert Comment

by:simon3270
ID: 35215847
This assumes that the "record" is a text line.  If this is a file sith some other format (fixed-length fields, binary values and so on) then "sed" won't work.
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Assisted Solution

by:woolmilkporc
woolmilkporc earned 50 total points
ID: 35215884
awk  '{if(substr($0,86,9)!="MB6     0") print}' largefile > largefile.tmp
mv largefile.tmp largefile

wmp
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Author Comment

by:Alaska Cowboy
ID: 35216001
simon and woolmilkporc, thanks ! I will try both options.
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Author Comment

by:Alaska Cowboy
ID: 35216126
ok, both worked ! thanks.
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